File 0119-xen-dont-try-setting-max-grants-mul.patch of Package qemu.9835

From 334e4a6e676ae7a90f5bd2cfe06020e23dac8598 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Fri, 22 Sep 2017 14:07:25 +0200
Subject: [PATCH] xen: dont try setting max grants multiple times

Trying to call xengnttab_set_max_grants() with the same file handle
might fail on some kernels, as this operation is allowed only once.

This is a problem for the qdisk backend as blk_connect() can be
called multiple times for a domain, e.g. in case grub-xen is being
used to boot it.

So instead of letting the generic backend code open the gnttab device
do it in blk_connect() and close it again in blk_disconnect.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
(cherry picked from commit e38c3e86dfffe3cc806d051b9deeab31836b196a)
[LD: BSC#1100408]
Signed-off-by: Larry Dewey <ldewey@suse.com>
---
 hw/block/xen_disk.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index b76640407c..ef13528cb0 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -1243,6 +1243,12 @@ static int blk_connect(struct XenDevice *xendev)
     /* Add on the number needed for the ring pages */
     max_grants += blkdev->nr_ring_ref;
 
+    blkdev->xendev.gnttabdev = xengnttab_open(NULL, 0);
+    if (blkdev->xendev.gnttabdev == NULL) {
+        xen_pv_printf(xendev, 0, "xengnttab_open failed: %s\n",
+                      strerror(errno));
+        return -1;
+    }
     if (xengnttab_set_max_grants(blkdev->xendev.gnttabdev, max_grants)) {
         xen_pv_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
                       strerror(errno));
@@ -1351,6 +1357,11 @@ static void blk_disconnect(struct XenDevice *xendev)
         }
         blkdev->feature_persistent = false;
     }
+
+    if (blkdev->xendev.gnttabdev) {
+        xengnttab_close(blkdev->xendev.gnttabdev);
+        blkdev->xendev.gnttabdev = NULL;
+    }
 }
 
 static int blk_free(struct XenDevice *xendev)
@@ -1358,9 +1369,7 @@ static int blk_free(struct XenDevice *xendev)
     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
     struct ioreq *ioreq;
 
-    if (blkdev->blk || blkdev->sring) {
-        blk_disconnect(xendev);
-    }
+    blk_disconnect(xendev);
 
     while (!QLIST_EMPTY(&blkdev->freelist)) {
         ioreq = QLIST_FIRST(&blkdev->freelist);
@@ -1397,7 +1406,6 @@ void xen_blk_resize_update(void *dev)
 
 struct XenDevOps xen_blkdev_ops = {
     .size       = sizeof(struct XenBlkDev),
-    .flags      = DEVOPS_FLAG_NEED_GNTDEV,
     .alloc      = blk_alloc,
     .init       = blk_init,
     .initialise    = blk_connect,